Zoonotic Cutaneous Leishmaniasis (ZCL) is a disease highly prevalent in North Africa and Middle East that is caused by Leishmania major. The TMRC program has three main goals :1-Describe the natural history of L. major infection as expressed in an endemic area especially with regard to asymptomatic infection .disease severity and risk of disease recurrence;2-Analyse the respective roles of factors specific of the vector(sand fly saliva ),or the parasite(intraspecies polymorphism) or the host immune response(innate or adaptative), in the clinical expression of ZCL with special emphasis on the identification of immune correlates of protection against primoinfection, disease occurrence or recurrence;3-Reinforce the application of Good Epidemiological Clinical and Laboratory Practices at all levels of programme implementation. In order to reach these goals, we shall conduct a large clinical prospective survey in a region endemic for ZCL. All enrolled individuals will be extensively investigated, clinically and immunologically, in order to accurately define their clinical history with regard to leishmania infection (including LST reactivity) as well as their in vitro immune responses to vector saliva components and parasite antigens at baseline Then an active detection of all ZCL cases, that will emerge among the cohort members will be conducted during the two following years .Leishmania isolates that could be grown from active lesions will be extensively investigated at the functional level in order to identify intraspecies diversity due to differential expression of virulence factors. The study will draw a picture of the natural history of L major infection in the region. In addition the clinical, immunological and parasitological informations generated by the program will be integrated into a multiparametric analysis. This will permit to identify immune correlates of protection that take into consideration the eventual effects of intraspecies functional polymorphism of L major and reservoir diversity. These data are of crucial importance for the development and evaluation of effective vaccines or antileishmanial drugs. PROJECT 1: L. major infection: Natural History and Determinants of Resistance (Ben Salah, A.) PROJECT 1 DESCRIPTION (provided by applicant): Determinants of susceptibility/resistance and natural history of L. major infection in endemic foci include environmental and host related risk factors. Our long term goal is to elucidate the natural history of L. major infection and to weight the relative importance of host related risk factors of cutaneous leishmaniasis (CL) emergence and severity considering the confounding effect of environmental factors influencing exposure. The specific hypothesis is that the natural history of L. major infection and the clinical expression of cutaneous leishmaniasis varies according to past history of transmission and to the type of biotope in the study area. Host related immunological surrogates of protection other than leishmanin skin test (LST) prior to transmission might explain resistance to the disease and might be used as efficacy criteria in the context of vaccines'evaluation in the field. Based on these observations the focus of project 1 is to refine by a prospective cohort population based study the estimation of the epidemetric parameters and clinical description of disease and transmission dynamics to improve the understanding of natural history of Leishmania (L.) major infection and its determinants. The specific aims are to: 1. Elucidate epidemetric parameters of L. major infection. We will use leishmanin skin test (LST) and clinical observations, the incidence of CL versus asymptomatic infection (LST???) in a two years prospective study in order to determine: i) the prevalence of LST positivity, ii) the rate of conversion and reversion of LST, iii) the incidence of symptomatic / asymptomatic infection, iv) the score severity of disease, v) the rate of recurrence, vi) the predictive value and the protection fraction of LST positivity. 2. To evaluate the relative importance of immune host related factors and environmental on the natural history and clinical expression of the disease. These include LST, cytotoxic immune response and antibodies against sand flies'saliva antigens, distance to colonized area by reservoirs, characteristics of dwelling and its compound, socio-economic factors and pathogenic properties of L. major isolates. 3. To develop and validate scales for severity of cutaneous lesions and quality of resulting scars. The scale items include size of the ulcer, color (hypopigmentation, hyperpigmentation, normal skin) and height.